This is from Chris Parrish's Fed Files blog
Chicago, IL Midway (MDW)
172.1500, N001
172.1500, N1A2
Chicao, IL O’Hare (ORD)
165.0750, 123.0 PL
165.0750, 131.8 PL
166.4625, 103.5 PL
166.2875, N004
168.9625, N001
169.1625, 123.0 PL
169.1625, N001
169.3000, 136.5 PL
172.1500, 103.5 PL
172.1500, 123.0 PL
172.1500, 136.5 PL
172.9000, 136.5 PL
I can confirm 172.150 is no longer in use at Midway.